Disposable hypodermic syringes are routinely used to administer medication to patients, thus presenting the requirement for proper disposal of the used and contaminated needles. In an emergency situation, this requirement sometimes is overlooked by the health care technician, whether for practical reasons or otherwise. Separate procedures for disposal are limited at best, consisting of (i) breaking the needle off in a special container which is separate from the syringe, or (ii) using special equipment to assemble or disassemble the syringe, both of which require extra steps for proper disposal of the contaminated device.
Even needles which are broken off still can present a hazard of so-called "needle strikes" to trash removal personnel. The potential for needle strikes to health care technicians and associated personnel can cause a high degree of anxiety and require expensive testing procedures of suspected needle strikes. More and more health care personnel are exposed to the risk of infection with the increasing care requirements of HIV- and AIDS-infected individuals, as well as the risk of hepatitis B and other infectious diseases.
Prior attempts to address safe disposal of contaminated needles by retracting the used needle into the cylinder of the syringe are illustrated by, for example, U.S. Pat. No. 4,995,870 disclosing a structure which requires loosening of the hub in order to release the needle from a plug and thus allow for withdrawal of the used needle into the cylinder of the syringe. While manipulating the hub to allow for the retraction, the technician must either expose his/her hand to the distal end of the used and possibly contaminated needle or use an auxiliary device for covering the tip of the used needle.
The needles of U.S. Pat. Nos. 4,026,287, 4,804,370, and 5,221,262 all are integral with the syringe cylinder rather than being removably attachable assemblies and, thus, prevent adaptability to syringes having a so-called Luer lock connection or other types of removable attachments for non-integral needle assemblies.
Some prior art devices have so-called extended needles which protrude proximally into the syringe cylinder past their points of attachment to the needle assembly such that complete expulsion of fluid from a cylinder is negated. Since fluid is not compressible, any residual fluid in the distal end of the cylinder opposes further distal movement of the piston once the proximal opening of the needle is blocked by the piston or otherwise. Under this condition, further distal movement of the piston and capturing of the extended needle for retraction is rendered non-functional or, at best, difficult. Still other prior art devices provide for a barbed, proximal end of the extended needle to be impaled in a full (as opposed to hollow) piston or the like to effect capture and retraction, thus requiring more force to effect the capture.
The above-described needle receivers of the prior art are integral with the corresponding piston stems and, thus, do not present a structure which lends itself to retrofitting existing piston stems of syringes which are widely used in the industry. In contrast, however, in U.S. Pat. No. 5,382,235 to Sak (the '235 patent), the entire contents of which are hereby incorporated by reference, the needle cannula is modified and a deflector member and capturer are retrofit to the syringe in order to safely retract and capture the used needle cannula. As shown in FIG. 1, the '235 patent provides an elongated piston stem 2' of a typical syringe having a distal end flange 4' which is engageable within groove 10 of generally hollow rubber piston 8. A capturer 40' is receivable within the hollow portion of rubber piston 8 and retained therein by completion of the attachment of the piston 8 to the flange 4'. The typical syringe also includes a cylinder 12' to the distal end of which a separate needle assembly is removably attachable 14. The point of attachment typically is provided with a Luer lock-type of connection which is well known to those skilled in the art. The needle assembly is illustrated as comprising the cannula 24' which is modified to have at least one lateral port 30' and a conically shaped deflector member 34' attachable thereto in a generally permanent manner. Cannula 24' also has grooves 32 to aid in attachment of the Luer lock-type hub 36' onto the cannula 24' by means of an adhesive. The distal end of cannula 24' is pointed for insertion into the patient and the proximal end thereof is sharpened for piercing of the rubber piston 8 upon complete expulsion of the fluid contained in cylinder 12'. In order to ensure uninterrupted and complete expulsion of fluid from cylinder 12', the so-called extended needle cannula 24' is provided with one or more of the lateral ports 30' for evacuation of any fluid remaining upon the proximal end of cannula 24'. Although retrofittable to existing syringes, the invention of the '235 patent discloses modification of the needle cannula such as annular grooves 32' and the manufacture of additional components such as deflector 34', all of which increase the cost of producing the device for capturing and receiving the needle cannula of the syringe.